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When an automobile moves over a wide, closed-loop of wire embedded in a road surface, the...

Question:

When an automobile moves over a wide, closed-loop of wire embedded in a road surface, the magnetic field of the Earth within the loop altered? Is a pulse of current produced? Can you cite a practical application for this at a traffic intersection?

Faraday Law of magnetic induction:

According to the Faraday law of magnetic induction, the strength of the induced field is directly proportional to the change in induced field in a unit time, when an electric field is induced in a region in which the magnetic field is changing in a unit time.

Answer and Explanation:


Some of the earth's magnetic field is enclosed in the closed-loop of wire embedded in a road surface. This magnetic field is altered momentarily due to the presence of iron parts when an automobile passes through it. Thus, the magnetic field of the earth is changed within the loop.


When there is a change in the magnetic field inside the wire on the road, then the eddy current is produced. It only flows in a closed-loop inside the conductor perpendicular to the magnetic field. The magnetic field of the current is directly proportional to the strength of the field and changes in flux. Thus, a pulse current is produced while moving an automobile on the road surface.


When an automobile passes through the traffic signal, then a loop of wire present in the traffic signal is used to detect the change in the electromagnetic field and shows a green signal. Thus, this is the practical application at a traffic intersection.


Learn more about this topic:

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Faraday's Law of Electromagnetic Induction: Equation and Application

from High School Physics: Help and Review

Chapter 13 / Lesson 10
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